Answer:
michelle, kaley, and Rebecca.
Explanation:
They have sold 100 tickets so far ($75), they need to sell 380 ($285) tickets in total and need to sell 280 more tickets.
Michelle was wrong because she should have divided 210 (how much more money they need to sell on tickets) into .75 (which is how much each ticket costs).
Kaley was wrong because she should have also divided 210 into .75 like Michelle.
Rebecca should have also divided 210 into .75.
Eva was the only correct one.